The field of the invention relates generally to methods and apparatus for measuring 3 dimensions (3D) on 2 dimensional (2D) images, and more particularly to methods and apparatus to conduct adaptive inspection for obtaining data that may include information in external and/or internal dimensions, surface condition information, and/or internal defect information.
Many components must be manufactured or maintained without surface or interior flaws. CMC (ceramic matrix composite) material is often used in fabricating aircraft components and other types of components. Sometimes, these components have, or develop, surface and/or interior flaws. Inspection for such flaws may be performed using known Infrared (IR) inspection systems in which an IR camera is used to provide 2D thickness images, along projection directions. The size of each defect is measured on a 2D IR image, which provides only information on the plane orthogonal to the direction of projection of the IR system. In addition, diffusivity information, which cannot be derived solely from 2D IR images, cannot be used to help characterize defect types on IR images. Also, as a result of optimization for their various applications, CMC components often have complex shapes and surfaces. Thus it may be difficult to measure a defect in three dimensions (3D) directly from an IR image.
Known methods for linking IR to CAD data have relied upon attaching a fixture to the part during inspection, as described in, for example, “[a] novel method for internal feature reconstruction based on Infrared thickness measurement” at the Third International Symposium on Multispectral Image Processing and Pattern Recognition, Proceedings of the SPIE, Volume 5286, pp. 230-237 (2003). Known methods for unrolling UT (ultrasonic tomographic) images use a mesh model rather than a solid CAD model. For example, U.S. Patent Application No. US20070217672A1 to Shaimon et al., entitled “Combined 2D and 3D nondestructive examination” discloses a technique of using 3D information as a visual aid for NDE (non-destructive examination) inspection. However, Shannon et al. does not describe nor suggest a specific method of unrolling IR images using 3D information. Rather, the methods disclosed therein are used to map 2D image onto 3D geometry, rather than mapping 3D information onto a 2D image.
A need thus exists for a device that can conveniently measure such defects in 3D directly from an acquired image. A need also exists for an inspection system in which acquired images and CAD data are linked to allow diffusivity compensation to improve inspection accuracy and/or to characterize defect types.